Flat panel display devices often operate using electron emitting structures, such as, for example, Spindt-type field emitters. These types of flat panel displays typically employ a metallized polyimide structure to focus or define the path of electrons emitted from the electron emitting structures. In one prior art approach, the polyimide structure is referred to as a "focus waffle." The focus waffle is comprised of a "sheet" or film-like structure having a plurality of openings formed therethrough. The focus waffle is disposed between the electron emitting structures and the faceplate such that emitted electrons pass through openings in the focus waffle structure, and are directed towards corresponding sub-pixel regions.
Additionally, the aforementioned sub-pixel regions on the faceplate of a flat panel display are typically separated by a polyimide-based opaque mesh-like structure commonly referred to as a black matrix. By separating sub-pixel regions, the polyimide black matrix prevents electrons directed at one sub-pixel from being "back-scattered" and striking another sub-pixel. In so doing, the polyimide black matrix helps maintain a flat panel display with sharp resolution. In addition, the polyimide black matrix is also used as a base on which to locate structures such as, for example, support walls.
Unfortunately, due to the extremely high cost of certain types of polyimide material (especially photo-patternable polyimide material), such prior art polyimide-based black matrix and focus waffle structures are extremely expensive. As a result, a conventional polyimide black matrix and/or a polyimide focus waffle introduces substantial additional costs to flat panel display fabrication. As yet another disadvantage, such prior art polyimide focus waffle and black matrix structures are a major source of contamination in flat panel display devices. Typically, such contamination results from electron bombardment of the polyimide black matrix or focus waffle during normal operation of the flat panel display device. Hence, such "dirty" polyimide focus waffle and polyimide black matrix structures introduce contaminate particles and/or desorbing gaseous species into the evacuated environment of the flat panel display device. These contaminate particles degrade the performance of the flat panel display device and reduce the effective lifetime of the flat panel display device via contamination of field emission surfaces and other possible mechanisms.
Thus, a need exists for a structure on the display cathode which effectively directs electrons emitted from electron emitters. A further need exists on the faceplate for a structure which effectively separates neighboring phosphor sub-pixels. A further need exists for a structure which meets the above-listed needs and which eliminates the use of expensive and contaminant producing polyimide material.